c------------------------------------------------------------------
      subroutine rent(atm,res,rnum,chn,nent)
c
c enter character strings res,atm into hash table for radii
c by assigning it a number nent
c
      include 'qdiffpar4.h'
c
c check to see if there is room
c
      if (irtot.eq.nrlist) then
          write(6,*)' radii list full- increase nrlist'
          stop 
      endif

      n = ichash(atm,res,rnum,chn)
      if (irnumb(n).ne.0) then
c
c slot filled
c run down linked list
c
9000      continue
          if (irlink(n).eq.0) goto 9001
          n = irlink(n)
          goto 9000
9001      continue
c
c  search for empty slot
c
          new = 1
9002      continue
          if (irnumb(new).eq.0) goto 9003
          new = new + 1
          goto 9002
9003      continue
c
c found one- add link
c
          irlink(n) = new
          n = new
      end if

c
c slot empty
c fill slot
c
      irnumb(n) = nent
      irlink(n) = 0
      irtot = irtot + 1
      return
      end
